Image Compression in Analog TV System Given Resolution = 780(H) x 585(V) Frame Rate = 50 pictures/second Number of cycles per line = 0.5 x 780 = 390 Number of cycles per frame = 390 x 585 = Number of cycles per second = x 50 = Bandwidth = 11.4MHz for monochrome picture Bandwidth = 34.2MHz for color picture (about 36MHz) Channel Bandwidth =6MHz for color picture A compression of about 6 times is necessary
Color Picture/ Frame 25 frames/sec BW=36 MHz
Color Picture/ Frame Half Picture/ Odd Field Half Picture/ Even Field 25 frames/sec BW=36 MHz 50 fields/sec BW=18MHz
Color Picture/ Frame Half Picture/ Odd Field Half Picture/ Even Field R GB R GB 25 frames/sec BW=36 MHz 50 fields/sec BW=18MHz 50 fields/sec BW=18MHz
Color Picture/ Frame Half Picture/ Odd Field Half Picture/ Even Field R GB R GB Y UV Y UV Frequency Interleaving Composite Video Signal 25 frames/sec BW=36 MHz 50 fields/sec BW=18MHz 50 fields/sec BW=18MHz 50 fields/sec BW=18MHz 50 fields/sec BW=6MHz
Color Picture/ Frame Half Picture/ Odd Field Half Picture/ Even Field R GB R GB Y UV Y UV 25 frames/sec BW=36 MHz 50 fields/sec BW=18MHz 50 fields/sec BW=18MHz 50 fields/sec BW=10MHz Y 6MHz2MHz U V
Color Picture/ Frame Half Picture/ Odd Field Half Picture/ Even Field R GB R GB Y UV Y UV Frequency Interleaving 25 frames/sec BW=36 MHz 50 fields/sec BW=18MHz 50 fields/sec BW=18MHz 50 fields/sec BW=10MHz Y 6MHz U+V
Color Picture/ Frame Half Picture/ Odd Field Half Picture/ Even Field R GB R GB Y UV Y UV Frequency Interleaving Composite Video Signal 25 frames/sec BW=36 MHz 50 fields/sec BW=18MHz 50 fields/sec BW=18MHz 50 fields/sec BW=10MHz 50 fields/sec BW=6MHz
Tradeoff Poorer resolution for fast motion picture Distortion in color due to frequency interleaving Distortion in luminance at high frequency Very little rooms for further compression